Gypsum drywalls, also known as wallboards, or just boards, are formed by sandwiching a core of wet gypsum plaster between two sheets of heavy paper. After the plaster core dries and sets, the sandwich becomes a rigid, very strong, and naturally fire-resistant building material. Gypsum in its natural state contains water, which releases steam when exposed to a fire's heat. Because the conversion of the water to steam consumes heat energy, heat transfer from the fire is retarded. Specific fire retardant compositions may also be added to the gypsum plaster to make drywall having yet a greater fire resistance. Gypsum drywall is an important building material throughout the world.
In building a structure, gypsum drywall is nailed to underlying supports to form the walls and other surfaces of the structure. Once nailed in place, the seams or joints between adjacent boards must be filled-in with drywall joint compound, also known in the art as “mud.” Once the mud is applied to the joint, the joint must be covered with a strip of heavy paper, which is then overcoated with additional mud in order to smooth out the appearance of the wall. Conventionally finished joints do not provide the same degree of fire retardancy as the drywall itself. Thus, in a structure fire the joints will pop their seams before the drywall itself is affected by the heat.
Accordingly, finishing the drywall installation is a time-consuming, manual process which delays the completion of the structure, as paint cannot be applied to the walls until after the drywall joints are filled, and they dry and set. Additionally, there occurs much waste of mud during the finishing process.